Project Summary/Abstract The research objectives of this fellowship are to determine the cellular tropisms of three mosquito-borne flaviviruses of public health importance ? Zika virus, dengue virus and yellow fever virus ? within their Aedes aegypti vectors and to define the roles of specific cell populations in viral dissemination and transmission. The aims are to 1) identify the specific cell populations critical for viral dissemination from the midgut to the salivary glands, and 2) define the impact of specific tissue tropisms on mosquito feeding behavior and viral transmission. Aim 1 will be accomplished by generating microRNA (miRNA) expression profiles for midgut, hemocyte and neuronal cell populations and selecting miRNAs that are highly differentially expressed in each population. We will confirm infection of cells expressing these miRNAs and generate cell-specific, miRNA-restricted viruses containing target sequences for cell-specific miRNAs to probe the roles of each cell type in viral dissemination. Aim 2 will be accomplished by using miRNA-restricted viruses to determine the effect of neuronal cell and salivary gland infection on mosquito feeding behaviors and subsequent transmission of the virus by observing infected mosquitoes feeding on mice and testing mice for the presence of virus. The data and tools produced by this work could aid the development of transmission control strategies that target viral replication in specific cell populations within the vector. Research and postdoctoral training activities will be undertaken at both Colorado State University and the Centers for Disease Control and Prevention in Fort Collins, CO. The sponsor and co- sponsor laboratories have complimentary research interests and facilities that will promote the success of this project. In addition to research, the training plan includes completion of coursework in next generation sequencing experiment and analysis, grant writing, and responsible conduct of research; participation in supervisory training; and attendance at various workshops, seminars and conferences to improve writing, presentation and career building skills.